Experimental evidence of the anti-parallel arrangement of methylammonium ions in perovskites

Orientation arrangement of methylammonium ions in hybrid organic−inorganic perovskite is still under debate because their tendency for alignment is expected to give rise to either ferroelectric or anti-ferroelectric behavior, which may influence the perovskite device performance. To resolve the debate surrounding the alignment of the organic cations in perovskite materials, we studied the dipole orientation by analysing the dielectric properties of the material. The dielectric permittivity has been investigated as a function of temperature with the data analysed using the Kirkwood–Frohlich–Onsager theory. From these results, we provide experimental evidence of the anti-parallel arrangement of methylammonium ions in hybrid organic−inorganic perovskite.